The present invention relates to airborne countermeasures systems that operate in either repeater or noise jamming modes and in particular to monitoring circuits for such systems.
Airborne repeater/noise jammer countermeasures system at present are not provided with built in monitors of RF power or modulation to notify the operator of a system failure. The prior art approach has been to propose that RF probes followed by crystal detectors be placed within both the forward and aft antennas to determine the presence of RF power. In the noise jamming mode the system output TWT can be checked by noting that the output power has exceeded the minimum acceptable level. Also, the presence of AM modulation (but not FM modulation such as swept spot) could be detected and recognized. However, in the repeater mode the output signal power may vary from near zero when no signals are received to saturation when large signals are received. Thus, the measure of power output in the repeater mode cannot be used as a measure of the system's operational state. There currently exists the need therefor for monitoring circuits that determine the operational state of an airborne countermeasures system when operating in either the noise or repeater jamming modes. In addition, the presence of either AM or FM modulation must be detected in either jamming mode.
The present invention is directed toward providing monitoring circuits that satisfy these and other system operating requirements.